Vacuum booster assemblies are commonly used as a means of assisting a driver during vehicle braking. By using a booster assembly, the force necessary for braking the vehicle is primarily provided by the vacuum booster assembly.
Most vacuum booster assemblies used in vehicle power brake systems utilize atmospheric pressure in generating their assist force. Most commonly, a diaphragm is disposed within a chamber and separates the chamber into first and second components. During a braking operation, one of the chambers is exposed to atmospheric pressure while the other chamber is exposed to a pressure which is less than atmospheric pressure (i.e. a vacuum source). The resulting pressure differential across the diaphragm causes the diaphragm to move thereby moving the associated linkage which assists the vehicle operator in the braking operation.
One common problem associated with diaphragms found in vacuum booster assemblies, is that they are prone to become dislodged during the assembly process. This not only leads to wasted time and money, but also can result in units which are prone to premature failure. More specifically, unless there is a severe misaligned between the diaphragm and its clamping structure, the vacuum booster assembly will function properly for a limited number of cycles, but because of the misalignment, it will prematurely fail (e.g. after ten or more cycles). Thus, simply testing the vacuum booster assemblies at the assembly site is not a completely satisfactory test for ensuring that the diaphragm is properly located and sealed within the chamber.
The problem of misalignment of the diaphragm during assembly is further exacerbated by the fact that most diaphragms used in vacuum booster assemblies tend to be serpentine in design. Thus they are designed having many bends and folds which are susceptible for contacting and causing the diaphragm to be dislodged during assembly of the vacuum booster.
U.S. Pat. Nos. 5,163,327; 4,971,523; 4,237,775; and 3,170,380 all deal with devices which employ diaphragms but none of them deal with the particular problems encountered when assembling vacuum boosters (serpentine diaphragms).
Accordingly, it is an object of this invention to provide a vacuum booster and a method for assembling a vacuum booster which overcomes the misalignment problems associated with serpentine vacuum booster diaphragms.
It is a further object of this invention to provide a vacuum booster assembly which incorporates a means for retaining an internal serpentine diaphragm in place during the assembly process.